Trackball



FIG. 1 is a rear elevational view of a trackball showing our new design.

FIG. 2 is a top plan view thereof,

FIG. 3 is a right side elevational view thereof,

FIG. 4 is a top, front, right side perspective view thereof on an enlarged scale.

FIG. 5 is a left side elevational view thereof. 

The ornamental design for a trackball, as shown and described. 